Contact copying process

ABSTRACT

COPIED IS DISPOSED WITH PRINTED OR OTHER IMAGES ADJACENT ENDS OF PARTICULAR CAPILLARIES, OR IF AN UNPRINTED OR UNIMAGED SURFACE PORTION OF THE SHEET TO BE COPIED IS DISPOSED AGAINST ENDS OF THE CAPILLARIES.   A PRESSURE SENSITIVE COPYING MATERIAL IS PROVIDED, WHICH UTILIZES A SHEET OF MATERIAL HAVING A PLURALITY OF CAPILLARY PORES FOR RECEIVING AND RETAINING AN IMAGE-FORMING MATERIAL FROM A CARRIER THEREFOR, WITH THE IMAGE-FORMING MATERIAL BEING DRAWN INTO CAPILLARIES AT DIFFERENT RATES, DEPENDING UPON WHETHER THE SHEET TO BE

United States Patent 3,600,212 CONTACT COPYING PROCESS Mortimer M. Labes, Rosemont, Pa., assignor to Drexel University, Philadelphia, Pa.

Original application Dec. 11, 1967, Ser. No. 689,666, now Patent No. 3,527,666, dated Sept. 8, 1970. Divided and this application Oct. 24, 1969, Ser. No. 871,181

Int. Cl. B41m /02, 3/12 US. Cl. 117-37 ABSTRACT OF THE DISCLOSURE A pressure sensitive copying material is provided, which utilizes a sheet of material having a plurality of capillary pores therein, for receiving and retaining an image-forming material from a carrier therefor, with the image-forming material being drawn into capillaries at different rates, depending upon whether the sheet to be copied is disposed with printed or other images adjacent ends of particular capillaries, or if an unprinted or unimaged surface portion of the sheet to be copied is disposed against ends of the capillaries.

This is a division of application Ser. No. 689,666, filed Dec. 11, 1967, now Pat. N0. 3,527,666.

BACKGROUND OF THE INVENTION Prior art copying techniqueswhich have been developed to provide a limited number of copies of each sheet to be copied have been principally of the photocopy type, requiring a light source, have required the use of stencils, or have been concerned with the application of toner particles to paper and the like by using carrier particles which are electrically charged. The copying techniques of the prior art are thus rather cumbersome, in many instances, in requiring expensive equipment, there being no provision for facilitating the copying of a limited number of sheets in a relatively simple and inexpensive manner. Also, the prior art is devoid of any such copying technique which is readily portable, and therefore adapted for use in environments other than those of a fully equipped office.

SUMMARY OF THE INVENTION The present invention seeks to fulfill a need which exists in the prior art, in providing a composite pressure sensitive copying element in which a carrier layer has been impregnated with an image-forming substance, and a transfer layer having a plurality of capillary-like pores is adapted to receive the image-forming substance from the carrier layer, when the transfer layer is placed against the surface of a sheet to be copied. The surface to be copied will generally have unmarked surface portions, and marked surface portions which are either printed, typewritten, or the like. This invention utilizes the difference in porosity between marked and unmarked surface portions, to effect a difference in flow rates of the image-forming substance through capillaries which have one end disposed against the sheet to be copied, some of the capillaries terminating against a marked surface portion of the sheet to be copied, and other of the capillaries terminating against an unmarked surface portion of the sheet to be copied, such that the rate of flow of the imageforming substance is greater in those capillaries which are disposed with one end against an unmarked surface portion of the sheet to be copied., By applying pressure to the carrier layer, and appropriately timing the application of such pressure, an image, either latent or actual will appear in either the carrier layer or the capillarystructured transfer layer, or both, such image being responsive to the amount of flow of the image-forming sub- 12 Claims Patented Aug. 17, 1971 stance through the capillaries of the transfer layer, hence responsive to the marked and unmarked surface portions of the sheet to be copied.

Accordingly, it is an object of this invention to provide a pressure sensitive copying element having a carrier layer which is impregnated with an image-forming substance, a transfer layer having a plurality of capillarylike pores therein, with both layers being sandwiched between fluid-impermeable layers, which prevent the transfer of an image-forming substance from the carrier layer to the transfer layer prior to removal of one of the fluid-impermeable layers.

It is another object of this invention toprovide an element as set forth in the object immediately above, wherein that fluid-impermeable layer which is provided against the transfer layer is readily separable therefrom.

It is a further object of this invention to provide a novel copying method, wherein a pressure sensitive copying element such as that discussed in the objects immediately above is provided, and wherein pressure is applied to the carrier layer, after the transfer layer is applied into direct engagement against the surface of a sheet to be copied, and the pressure applied to the carrier layer facilitates the expulsion of entrapped air from. the capillaries of the transfer layer, at a rate dependent on the porosity of the particular surface portion of the sheet to be copied, disposed immediately beneath the capillaries, such surface porosity varying between marked or indiciabearing and unmarked or indicia-free surface areas, leaving an image on either of the carrier or transfer layers.

It is another object of this invention to accomplish the object described immediately above, wherein the time period of pressure application is discontinued prior to all entrapped air being forced out of any of the capillary pores.

It is a further object of this invention to accomplish the above objects, wherein the image formed on either of the carrier or transfer layers may be either latent or actual.

Other objects and advantages of the present invention will be readily apparent to those skilled in the art from the following brief description of the drawing figures, detailed description of the invention, and the appended claims.

In the drawings:

FIG. 1 is a highly enlarged schematic cross-sectional view through a composite copying element or material of this invention.

FIG. 2 is a view generally similar to that of FIG. 1, but wherein a lowermost fluid-impermeable layer has been removed, and the copying element has been placed in overlying relation to a printed sheet to be copied, with pressure applied.

FIG. 3 is a fragmentary view taken generally along the line IIIIII of FIG. 2, of an image formed in a substantially transparent carrier layer of a copying element of this invention, by complete flow of an image-forming substance from the carrier layer with only partial flow of the image-forming substance into some of the capillary pores of a transfer layer, leaving a generally T-shaped image in the carrier layer, corresponding generally to a marking or indicia on the surface of the sheet to be copied.

FIG. 4 is a view generally similar to that of FIG. 3, but taken along the line IVIV of FIG. 2, wherein differences of depth of image-forming substance in capillary tubes create a difference in image shading between portions of the transfer layer which overlie printed portions of the sheet to be copied, and portions of the transfer layer which overlie unprinted portions of the sheet to be copied.

Referring now to the drawings in detail, reference is first made to FIG. 1, wherein there is illustrated a composite copying element, generally designated by the numeral disposed on a planar surface 11.

The composite element 10 includes a carrier layer 12, which is impregnated with an image-forming substance 13, a transfer layer 14, an upper fluid-impermeable layer 15, and a lower fluid-impermeable layer 16.

The carrier layer 12 may be constructed of any material suitable liquid impregnation and retention, such as a fibrous or sponge-like material, or the like. The material 12 may be compressible and porous, such as a felted material, or may be of sponge-like neoprene, latex foam, or of fibrous glass construction.

The image-forming substance 13 may comprise an ink or dye or any other suitable marking or coloring substance. Additionally, the image-forming substance 13 may be substantially colorless, leaving no visible indication to the naked eye, but which, when treated with chemicals, chemical solutions, heat or light would be transformed from a latent image to an actual image.

The transfer layer 14 is generally a soft capillary membrane material having an ordered pore structure preferably, but not limited to the range of 10 to 10 pores per centimeter? An exemplary but not limiting example of such transfer layer material may comprise that commercially available material known as Nuclepore.

The fluid-impermeable or non-porous layer 15 may comprise an integral skin portion of the carrier layer 12, or may comprise a separate layer of any suitable fluidimpermeability film. Exemplary materials for the layer 15 are those such as polyvinyl chloride, cellophane, or any of the various resin films, or the like, having desirable fluid-impermeable characteristics.

The lower fluid-impermeable or non-porous layer 16 is generally a distinct layer manually separable from the transfer layer 14, and may be constructed from any suitable material such as those set forth above as exemplary constructions for the layer 15.

In the fragmentary microscopic sectional schematic view of FIG. 1, the transfer layer 14 is illustrated as having 5 capillary pores 17, 18, 20, 21 and 22. As the image-forming being separated from one another by a wall portion 23.

With reference to FIG. 2, the element 10 is illustrated as having the lower fluid-impermeable monporous layer 16 removed therefrom, with the element 10 being disposed in overlying relation to the sheet 24, which is to be copied, with the lower-most open ends of the pores 17, 18, 20, 21 and 22 of the transfer layer 14 disposed against an upper surface 25 of the sheet to be copied 24.

The sheet 24 may comprise a sheet of paper or the like, having printed, typed, or other indica-bearing surface portions 26, 27, and 28 thereon, and unmarked or indiciafree surface portions such as those 30 and 31. It is to be noted, that while the sheet 24 is referred to as a sheet of paper or the like, any structure having indicia or other markings thereon may be copied, as long as such structure is sufiiciently porous, to permit the passage of air from capillary ends disposed thereagainst.

While the printed surface portions 26, 27 and 28 are illustrated in FIG. 2 as being disposed directly beneath the capillary pores 17, and 22, for exemplary purposes, it is to be noted that a given printed or marked surface portion, such as, for example, the letter T may be disposed beneath hundreds or more individual capillary pores.

In a copying operation, with the non-porous sheet 16 removed from the composite element 10, and the element 10 then being applied in overlying relation to a printed sheet 24 or the like, disposed on a generally planar surface 11, pressure P is then applied to the upper surface of the element 10, preferably by engagement of a pressure plate (not shown) against the upper surface of the layer 15, such that pressure is transmitted to the carrier layer 12, thereby forcing the image-forming substance 13 into the 4 capillary pores 17, 18, 20, 21 and 22. As the image-forming substance 13 is forced into the capillary pores, captured air or the like is forced outwardly through the lower ends of the pores, as illustrated in FIG. 2, through the porous sheet 24, which is to be copied.

It has been found, that the porosity of a porous sheet 24 is decreased when such a sheet is marked or bears other indicia, such as is effected in a printing, typing or the like operation. In fact, it has been found that in some instances, the porosity of an unprinted portion of a sheet of material is twice as great as the porosity of a printed portion of the sheet of material. Employing this feature to advantage, it has been found that upon application of a pressure P in the manner above described, the imageforming substance 13 will descend or flow into capillary pores 18 and 21 which are disposed above unmarked or indicia-free surface portions of the sheet 24, at a greater rate than will the substance 13 flow through the capillary pores 17, 20 and 22 which overlie marked or indiciabearing surface portions 26, 27, and 28 of the sheet 24. If the porosity ratio of unmarked sheet portions to marked sheet portions is represented by a factor of two to one, in a given time interval during which pressure P is applied to the element 10, substantially twice as much imageforming substance 13 will descend into the capillary pores 18 and 21 as will descend into the capillary pores 17, 20 and 22.

It will be noted that the timing of the application of pressure P to the element 10 should be carefully controlled, such that the image-forming substance 13 descending in the capillary pores 18 and 21 will not descend an amount sufiicient to contact the surface portions 30 and 31 of the sheet 24, to undesirably mark the same.

When the desired predetermined length of time has passed, the element 10 may be removed from the sheet 24, and the layers 12 and 14 may then be separated, thereby allowing the image-forming substance 13 which is then present in those layers to dry upon contact with air, substance 13 having previously been prevented from air contact and hence from drying in the composite element 10 due to the presence of the fluid-impermeable layer 15 and 16.

The image formed in the layer 14 may appear substantially as that shown in FIG. 4, with the composite area formed by the liquid substance 13 which is dried in the plurality of capillary pores 17, 20, and 22 which disposed over marked or indicia bearing surface portions of the sheet 24 being substantially lighter than the area formed by the image-forming substance which is of greater depth in the pores 18 and 21, such difference in depth of dried image-forming substance giving a visual indication such. as that illustrated in FIG. 4 for the letter T, in which the lighter area comprising the T formation is effected by a composite formation of pores having an image-forming substance of lesser depth, and the outlining area for the letter T is effected by a composite of those pores of greater depth of dried image-forming substance 13. It will be apparent that the image evidenced by FIG. 4 is a negative image as compared to the image or marking originally present on the surface 25 of the sheet 24 which is copied.

It is conceviable that the transfer layer 14 may be constructed of a double thickness sheet having an upper layer (not shown) which is penetrated by the imageforming substance 13 pressing into all of the capillary pores 17, 18, 20, 21, 22 and having a lower layer below the mating surface for such layer portions, such that the image-forming substance 13 penetrates below such mating surface only through those capillary pores 18 and 21 which are not disposed over marked surface portions of the sheet 24 to be copied. In such a structure, upon separation of the two layer portions of the transfer layer 14, the negative image illustrated in FIG. 4 would be formed only by a composite of a plurality of pores 18 and 21, in which the image-forming substance 13 had penetrated, leaving a void or completely blank area such as that which comprises the T formation in FIG. 4, formed by separating the lower layer portion of the layer 14 from its upper layer portion prior to penetration of the pores 17, 20, and 22 of the lower layer portion by the image-forming substance 13.

After discontinuing the application of pressure P, and separation of the carrier layer 12 from the transfer layer 14 and the fluid-impermeable layer 15, a positive image is left on the carrier 12, by the image-forming substance 13 which is not received completely within capillary pores of the transfer layer 14, but which remains within the carrier layer 12, such as that shown disposed above capillary pores 17 20, and 22 in FIG 2. Upon separation of the carrier layer 12 from the other layers, and drying of the image-forming substance 13 upon air contact, a mirror image of the printed indicia 26, 27, and 28 on the surface 25 of the sheet 24 appears on the under surface of the carrier layer 12. However, should the carrier layer 12 be, for example, of transparent construction, and viewed from above, along the section line III-III of FIG. 2, a positive image would be available on the upper surface of the layer 12, directly corresponding to the original marking or indicia which appears on the upper surface 25 of the sheet 24 which is copied. With reference to FIG. 3, there is illustrated the view which would appear along the section line III-III, or upon the upper surface of the layer 12, if a letter T appeared on the surface 25 of the sheet 24, the letter T being formed by the residual image-forming material which remains within the carrier layer 12, disposed directLy above those capillary pores which are, in themselves disposed directly above comparable portion of a marking or indicia represented by the letter T on the surface 25 of the sheet 24.

As has been mentioned above, should the image-forming substance be of a type adapted to leave only a latent image, after termination of the application of pressure P to the composite element 10, it may be desirable to subject either of the layers 12 or 14 to additional operations or processes, in order to develop a visible image thereon responsive to the differential flow rate of the image-forming substance 13 through the capillary pores. Such later procedures may or may not be necessary depending upon the type of image-forming substance 13 which is utilized.

It will be apparent that the terms indicia and marking should be read in the broadest sense, to include any marking, printing, writing, etc., which may be desired to be copied. Also, the various materials set forth herein are exemplary only, and this invention is not intended to be limited to the specific materials, or to specific manners of operation. In some instances it may be desirable to place the sheet to be copied in overlying relation to the composite element 10, and to exert pressure onto the sheet which is to be copied, which would be transferred downward for compression of the carrier layer, and consequently result in a rise of image-forming substance into the capillary pores. Such modifications and others as well, are to be considered to be within the scope of this invention.

The particular embodiments illustrated and described are exemplary only, and are not intended to limit the scope of this invention, as defined in the appended claims.

What is claimed is:

1. A method of copying from a porous member, comprising the steps of providing a composite copying element having a carrier layer with an image-forming substance impregnated therein and a transfer layer disposed thereagainst, the transfer layer having capillary pores extending therethrough, providing a porous member having portions of different porosities, placing the composite element against the porous member with capillary openings terminating against surface portions of the porous member, applying pressure substantially uniformly to the carrier layer to force the image-forming substance into capillary pores of the transfer member, with the image-forming substance which enters the pores forcing air out of the pores through the porous member at different rates, depending upon the porosity of the particular portion of the porous member disposed thereagainst.

2. The method of claim 1, wherein the time period of pressure application is dependent upon the flow of the image-forming substance through the capillary pores.

3. The method of claim 2, wherein application of pressure is discontinued prior to all air being forced out of any of the pores.

4. The method of claim 1, wherein non-porous layers are provided on at least one surface of the composite element, including the step of removing that non-porous layer adjacent the transfer layer prior to placing the composite element against the porous member.

5. The method of claim 4, wherein the porous member has indicia therein, with those portions of the porous member which are of different porosities comprising indicia-bearing and indicia-free surface portions, and wherein the carrier layer and transfer layers are then separated leaving an image in at least one of said layers, the image being determined by the indicia configuration on the porous member, and the time period of pressure application is dependent upon the flow of the image-forming substance through the capillary pores and wherein application of pressure is discontinued prior to all air being forced out of any of the pores.

6. The method of claim 1, wherein the porous member has indicia therein, with those portions of the porous member which are of different porosities comprising indicia-bearing and indicia-free surface portions, and wherein the carrier layer and transfer layers are then separated leaving an image in at least one of said layers, the image being determined by the indicia configuration on the porous member.

7. The method of claim 6, wherein the image formed is latent.

8. The method of claim 6, wherein the image formed is actual.

9. The method of claim 6, wherein the image appears on the transfer layer.

10. The method of claim 9, wherein indicia-bearing and indicia-free portions of the porous member result respectively as indicia-free and indicia-bearing images on the transfer layer.

11. The method of claim 6, wherein the image appears on the carrier layer.

12. The method of claim 11, wherein indicia-bearing and indicia-free portions of the porous member result respectively as indicia-bearing and indicia-free images on the carrier layer.

References Cited U.S. Cl. X.R. 

